GB1104652A - Landing gear system - Google Patents

Abstract

1,104,652. Retractable aircraft undercarriages. IN - FLIGHT DEVICES CORPORATION 8 June, 1965 [8 June, 1964], No. 24253/65. Headings B7G and B7W. Aircraft landing gear is retracted or extended by electric, hydraulic or pneumatic power under pilot control, and a control system is provided to extend the gear automatically, or prevent the pilot retracting it, under certain conditions. As described the gear is operated by an electric motor having " UP " and " DOWN " windings connected to a pilot's control switch 10, the supply to which, from a busbar 22, may be cut off by a first switch 3 operated by a pressure switch α which is closed when the airspeed is below 1À1 Vs (Vs being the stalling speed), or below a predetermined altitude. Hence the pilot cannot retract the gear under these conditions. A second switch 4, operating below 1À5 Vs, or some higher altitude, by a pressure switch #, by-passes the pilot's control to energize the " DOWN " winding, automatically lowering the gear, if one of two other sensing devices γ and # is actuated. The device γ is actuated on reduced engine power, being sensitive to manifold pressure or throttle position or alternatively to thrust vector angle of a direct lift engine; as described there are two devices γ, one for each engine. The device # is actuated when the flaps are lowered below a certain angle, or when propellers are put into fine pitch. Switches actuated by the devices γ and # are also in series with the first switch 3, so that the gear can only be raised above 1À1 Vs when the flaps are up and the engine power above a predetermined level. The control system may be over-ridden to allow normal pilot operation, and a warning light 14 and horn 15 are then operated. Further lights are provided to indicate (a) when the flaps are down, (b) when the landing gear is down, (c) when the landing gear is up, and (d) when the pilot's control has selected gear retraction and the control system is holding it down. The test switch 13 when closed, should cause all the warning lights and the horn to operate when the aircraft is at rest on the ground and the system is operative.